A low-dropout (LDO) voltage regulator is used generally in power feeding equipment to supply a regulated voltage. Such a LDO voltage regulator is configured of an integrated circuit to be usable in various electric products. Some or all of the elements included in the LDO voltage regulator may incorporate standard digital CMOS technology.
The configuration of the conventional LDO regulator is disclosed in U.S. Pat. No. 6,046,577 entitled “LOW-DROPOUT VOLTAGE REGULATOR INCORPORATING A CURRENT EFFICIENT TRANSIENT RESPONSE BOOST CIRCUIT,” U.S. Patent Publication No. 2007/0241728 entitled “LOW-DROPOUT VOLTAGE REGULATOR WITH A VOLTAGE SLEW RATE EFFICIENT TRANSIENT RESPONSE BOOST CIRCUIT,” U.S. Pat. Nos. 6,710,583 and 6,304,31 entitled “LOW DROPOUT VOLTAGE REGULATOR WITH NON-MILLER FREQUENCY COMPENSATION.”
According to the LDO voltage regulator disclosed hereinabove, loop is eliminated by using an error amplifier under a time-varying load current atmosphere. However, it is limited to improve transient response of an output voltage by using only error amplifier and thus the above conventional LDO regulator would have a good slew rate of the stable output voltage.